Pressure responsive device for indicating the magnitude of pressure changes

ABSTRACT

A pressure responsive device for indicating the magnitude of pressure changes as they occur in a confined body of fluid. The device is characterized by a flexible tubular member communicating with the body of fluid having a wall portion thereof supported against elongation whereby the tubular member is caused to assume an arcuate configuration as the magnitude of the pressure increases, and a substantially linear configuration as the magnitude of the pressure of the body of fluid decreases. The device has particular utility with truck tires and the like for alerting drivers of reduced tire pressures.

United States Patent [1 1 1 11 3,756,190 Kendall 1 Sept. 4, 1973PRESSURE RESPONSIVE DEVICE FOR 3,680,523 8/1972 Gaskins 73/146.8

INDICATING THE MAGNITUDE or PRESSURE CHANGES Harland R. Kendall, 1313Chatham Dr., Visalia, Calif. 93277 Filed: Feb. 18, 1972 Appl. N0.:227,537

Inventor:

U.S. Cl.....; 116/34 R, 73/146.3 Int. Cl. B60c 23/04 Field of Search73/146.3, 146.8, 73/388 R, 410, 418, 411, 409; 92/92; 116/34 RReferences Cited UNITED STATES PATENTS 2/1971 Rich 73/410 illllllllllllll! l...

NIH-il ll IHHHHIHHJHI- ll llllllllllllu r--*" if" PrimaryExaminer-Donald O. Woodie] AttorneyHerbert A. Huebner et al.

[57] ABSTRACT A pressure responsive device for indicating the magnitudeof pressure changes as they occur in a confined body of fluid. Thedevice is characterized by a flexible tubular member communicating withthe body of fluid having a wall portion thereof supported againstelongation whereby the tubular member is caused to assume an arcuateconfiguration as the magnitude of the pressure increases, and asubstantially linear configuration as the magnitude of the pressure ofthe body of fluid decreases. The device has particular utility withtruck tires and the like for alerting drivers of reduced tire pressures.r

7 Claims, 7 Drawing Figures.

PAIENTEME? Mara 3756390 mum...

mnmumum I i BACKGROUND OF THE INVENTION The invention relates topressure responsive devices and more particularly to a pressureresponsive device for indicating the magnitude of changes in pressureexperienced in a body of fluid confined within the tire of an operatingvehicle.

As is appreciated by those familiar with the operation of dual-wheelvehicles, such as those frequently employed on highways in truckingcommerce, it is quite difficult to detect low pressure conditions asthey occur in the tires of operating vehicles. The problem becomesparticularly bothersome where one tire of a pair of tires mounted on adual wheel experiences a loss of pressure. This problem becomes acute ininstances where the loss in pressure is experienced in the inboard tiresince the visual examination of the tire frequently is impeded. It hasbeen postulated that low tires account for from to percent of vehicleoperation costs. Furthermore, it is not uncommon for fires to develop asa direct consequence of under-inflated tires.

In order to avoid undesired consequences of underinflated tires, manyoperators periodically halt their vehicles, dismount and examine eachtire in turn. While this technique is, in many instances, successfullyemployed in reducing operating costs, it is recognized that the vehicleoperators often employ their vehiclesunder conditions which severelydiscourage any use of the technique.

In an effort to solve this perplexing problem, a use of various deviceshas been suggested. Such are typified by the device shown in UnitedStates Letters Patent No. 3,527,189 which issued to Mark J. Perry, Sept.8, 1970.

Of course, as is well recognized with those familiar with the truckingindustry, any device employed on the wheels of vehicles and the likemust, in order to function efficiently, be of a simple design, includingminimal mechanical components, be easily maintenanced, and besubstantially resistant to the effects of ice, water, snow, mud and thelike.

Therefore, any device which is successfully employed on the wheels ofoperating vehicles, for indicating losses in tire pressures, as theyoccur, must be simple, easy to maintain, economic, and efficient in itsoperation.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of theinstant invention to provide an improved pressure responsive device.

It is another object to provide an improved pressure responsive devicefor indicating the magnitude of pressure changes as they occur in aconfined body of fluid.

It is another object to provide a pressure responsive device forindicating the magnitude of pressure changes as they occur in the tiresmounted on the wheels of operating vehicles.

It is another object to provide an improved pressure responsive devicefor use with the wheel of an operating vehicle, including a flexibletubular member, communicating with the fulid of a tire mounted on thewheel, responsive to changes in the pressure of the fluid for causingthe tubular member to assume a retracted arcuate configuration as themagnitude of pressure is increased above a predetermined level, and asubstantially linear configuration as the magnitude of the pressure isdecreased below a predetermined level.

These and other objects and advantages are achieved through the use of aflexible tubular member communieating with the fluid of the tire mountedon the wheel of a vehicle responsive to changes in pressure of the fluidfor assuming an inwardly directed arcuate configuration as the magnitudeof the pressure increases and in extended linear configuration as themagnitude of the pressure decreases.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectionedelevation of a dual wheel equipped with a pair of pressure responsivedevices, each of which includes a flexible tubular member communicatingwith the fluid confined within the tires mounted on the wheel.

FIG. 2 is afragmented side view of one of the devices shown in FIG. 1.

FIG. 3 is a partially sectioned view, on an enlarged scale, takengenerally along line 3#--3 of FIG. 2.

FIG. 4 is a cross-sectional view taken generally along line 4-4 of FIG.3.

FIG. 5 is a cross-sectional view of one bular member.

FIG. 6 is a cross-sectional view of another form of the tubular member.

FIG. 7 is a side elevation of still another form of the tubular memberemployed by the device of the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingswherein like reference characters designate like or corresponding partsthroughout the several views, there is shown in FIG. 1 an elevationalview of a dual wheel, generally designated 10, having mounted thereon afirst and a second pneumatic tire, l2 and 14, respectively.

The dual wheel 10 is conveniently supported on an axle, designated 16 ofa vehicle, such as frequently is provided for buses, trucks, and similarmachines not shown. The particular manner in which the wheel 10 ismounted on the axle 16 is a matter of convenience only form of the tuandforms no specific part of the instant invention.

Therefore, a detailed description of the dual wheel 10 and its mountingis omitted in the interest of brevity.

The dual wheel 10 is provided with a pair of pressure responsivedevices, each being generally designated 20. Since the devices 20 are ofa similar design and function in a similar manner for similar purposes,a detailed description of a single device is deemed sufficient toprovide a complete understanding of the invention.

As shown, each of the devices 20 is affixed to the outermost rim,designated 22, of the dual wheel 10. As a practical matter, the deviceis supported within a suitable bracket 24 securely fixed to the rim 22,within the cavity 26 of the wheel 10. Of course, it should beappreciated that the bracket 24 is fixed to the rim 22 by any suitablemeans, including rivets, spot-welds and the like. Since the particularmanner in which the bracket 24 is affixed to the rim 22 is deemed to bea matter of conveniece, a detailed description is omitted. In any event,it is to be understood that the bracket 24 is secured to the rim 22within the cavity 26 and accommodates a releasable coupling of thedevice 20 to the rim 22.

The pressure responsive device 20 includes a base block 30 seated withinthe bracket 24 and having a bore 32 extended therethrough. Communicatingwith the bore 32 is an angularly related bore 34. The bore 32 extendsalong an axis generally paralleling the axis of symmetry of the axle 16while the bore 34 is extended radially with respect thereto. Within theinboard end of the bore 32 there is threaded a pneumatic fitting 36,while a similar pneumatic fitting 38 is threadingly received within theoutboard end of the bore 32. Within the bore 34 there is seated apneumatic fitting 39 consisting of a valve stem having a valve core, notdesignated. The fitting 36 can, in practice, be considered an inletfitting for the block 30 while the fitting 38 functions as a couplingfor a flexible tubular body 40. This body 40 has affixed to itsoutermost end a flag 42 so that the body, in effect, assumes thecharacteristics of a flexible staff for the flag.

The body 40 is secured to the fitting 38 by a suitable hose-clamp 44while the flag 42 is united with the tubular body 40 by means of ahose-clamp 46 which binds the body 40 to a supporting stem 48. It will,of course, be appreciated that the particular manner in which the body40 is mounted on the fitting 38 and/or coupled with the flag 42 is amatter of convenience and can be varied as desired. In practice, theflag 42 includes, at the distal end of the stem 48, a spherical mass 50.Preferably, the mass 50 is formed of any suitable material and is of areadily perceptible color for attracting the attention of an operator ofa vehicle equipped with the dual wheel 10. Furthermore, the mass 50 isof a selected weight, which develops forces of a determinable magnitudewhen angular acceleration is imparted to the wheel 10.

In order to couple the base block 30 with a given one of the tires, aconduit 52, preferably of flexible material, is mounted on the fitting36 in a manner quite similar to that in which the body 40 is mounted onthe fitting 38. The opposite end of the conduit 52 is secured to a valvestem, designated 54, provided for one of the tires for filling the tireand gauging the pressure developed within the associated one of thetires. As a practical matter, the valve core of the stem 54 can beremoved, if so desired, from the valve stem whereby the tubular body 40communicates directly with the pneumatic pressure confined within thetire from which the conduit 52 is extended.

The body 40, in operation, responds to pressure exceeding apredetermined magnitude established within the tire to which the conduit52 is affixed and curls into an arcuate configuration extending radiallytoward the axle l6 and, in the presence of pressure beneath thatmagnitude, extends laterally from the cavity 26 of the wheel 10. Sincethe spherical mass 50 is subject to the effects of centrifugal forcesacting thereon as the wheel is rotated, there is a distinct tendency forthe spherical mass 50 to be forced outwardly from the wheel 10.Therefore, in order for the body 40 to retain an arcuate configuration,the pressure within the associated tire must be of a magnitude such thatthe body is capable of withstanding the effects of the centrifugalforces applied to the mass 50. i The arcuate configuration operativelyassumed by the body 40 is facilitated by its construction, which maytake any one of several forms. As shown in FIG. 5, the

body 40 is formed of a flexible, resilient material, such as rubber,extruded or otherwise formed into a tubular member having a thickenedwall portion 56 extending longitudinally along the wall of the body 40nearest the axle 16. Thus the wall portion 56 tends to more readilywithstand deformation than the wall portion diametrically oppositethereto. Therefore, as pressure is increased within the body 40, thewall portion of the body opposite the thickened wall portion 56 iselongated causing the body 40 to assume a desired arcuate configuration,illustrated in FIG. 3, whereby the mass 50 is positioned within thecavity 26 adjacent to the axle 16. Once the pneumatic pressure withinthe body 40 is sufficiently depleted, the resiliency of the materialfrom which the body is formed tends to return the body 40 to a linearconfiguration. This action, of course, is accelerated in instances wherecentrifugal forces are simultaneously applied to the mass 50.

Where preferred, the body 40 is provided with an elongated, linear leafspring 58 extended longitudinally along the wall of the body 40 nearestthe axle 16. As illustrated in FIG. 6, the spring 58 can be embedded inthe wall of the body employing any suitable technique, such asvulcanizing and the like. The function of the leaf spring 58 is topreclude elongation of the adjacent portion of the wall of the body 40as pressurization within the body occurs and the portion of the wallopposite the leaf spring responsively elongates. Thus, a body 40 alsoprovided with the spring 58 is caused to assume the'arcuateconfiguration, illustrated in FIG. 3. This body is returned to thesubstantially linear configuration as pressure in the body is depletedand the forces of recovery within the material from which the body isformed and the leaf spring causes the elongated wall portion to contractand the spring to assume its original linear configuration.

As a practical matter, a device 20 having a tubular body 40 providedwith truncated annular corrugations or bellow-like pleats formed along awall portion 60 can be employed quite satisfactorily. When the body 40is pleated, in the manner illustrated in FIG. 7, the wall portion 60 ispermitted to elongate for deforming the body 40. Of course, the wallportion 60 cannot be relied upon to return the body 40 to its original,elongated configuration. Hence, the wall portion of the body 40 oppositethe pleated wall portion 60, acting in conjunction with appliedcentrifugal forces, serves to apply the required forces of recovery forreturning the body 40 to its elongated configuration.

Consequently, where the device 20 employs a tubular body 40 having apleated wall, it is often preferred to utilize a thickened wall portion56 or, alternatively, a leaf spring 58 in order to assure a recovery ofthe body 40 into a substantially linear configuration, once pneumaticpressure within the'associated tire is depleted, for positioning themass 50 outwardly from the cavity 26. It will, of course, be understoodthat matters such as the pneumatic pressure developed within the body40, the length and the back-bone of the body, the weight of the mass 50and the angular velocity imparted to the device 20 all tend to affectthe ultimate configuration assumed by the body 40, regardless of theparticular form utilized, when the flag 42 is withdrawn into the cavity26, as well as when it is extended therefrom.

OPERATION It is believed that in view of the foregoing description, theoperation of the device will be readily understood and it will bebriefly reviewed at this point.

It is to be understood that the pressure responsive device 20 can beemployed in an environment quite different from that hereinbeforedescribed. For example, a single device 20 may be mounted on other thandual wheels and employed for indicating the magnitude of changes inpressure within a single tire for any vehicle.

Furthermore, the utility of the device 20 is not limited to indicatingthe magnitude of changes in pneumatic pressures experienced withinpneumatic tires for vehicles. However, it is to be understood that thedevice 20 is particularly suited for such use. Accordingly, for purposesof describing the function of the device 20, reference is made to theaforementioned dual wheel having pneumatic tires 12 and 14 mounted onthe rims thereof.

As shown in FIG. 1, the dual wheel 10 includes a pair of pressureresponsive devices 20, one of which is connected with the inboard tire12 while the other device is coupled with the outboard tire 14. Wheredesired, the spherical masses 50 are of different colors for readilyidentifying the tires with which the body 40 of the device 20 isassociated.

It will be appreciated, of course, that the operation of the devices 20is essentially the same, regardless of whether the body 40 includes athickened wall portion 56, as shown in FIG. 5, a leaf spring 58, asillustrated in FIG. 6, or a pleated wall portion 60, as shown in FIG. 7.Since the purpose of the body 40, in each instance, is to facilitate analternate configuring of the body 40 to both arcuate and linearconfigurations, in response to pressure changes of predeterminedmagnitudes occurring within the associated tire, the device 20 functionsin substantially the same manner regardless of the particular form ofthe body employed.

The body 40, of each device 20, through a base block 30 and a conduit52, is in direct communication with a body of fluid or air confinedwithin the tire associated therewith. The pressure of this body offluid, when of a given magnitude, causes the body 40 to deform and thusposition the mass 50 out of the line of vision of an operator for thevehicle. This occurs as the pressure of the fluid within the body 40causes an appropriate portion of the wall opposite the wall portion ofthe body 40 adjacent the axle 16 of the wheel to elongate for impartingan arcuate configuration to the body 40. The magnitude at whichdeformation occurs can empirically be determined, if so desired.Assuming the magnitude of the pressure is sufficiently great, theimparted arcuate configuration is maintained during the operation of thevehicle to which the dual wheel 10 is affixed.

However, in the event pressure within the associated tire issufficiently depleted, the combined effects of the recovery forces ofthe elongated portion of the wall of the body 40 and the centrifugalforces acting on the mass 50 of the flag 42 cause the body 40 toapproach a linear configuration, whereby the spherical mass 50 isextended beyond the cavity 26 of the wheel 10 into the line of vision ofthe operator.

Of course, the extent to which the spherical mass 50 is extended beyondthe cavity 26 of the wheel 10 can be varied simply by varying the lengthof the tubular body 40. Preferably, however, the tubular body 40 iscaused to assume a linear configuration once the pressure within theassociated tire falls beneath the predetermined magnitude.

In order to return the flag 42 to the cavity 26, the pressure within theassociated tire is elevated to a predetermined magnitude for againcausing the body 40 to assume an arcuate configuration fbr therebyretracting the flag 42, including the mass 50, to the cavity.

In view of the foregoing, it should readily be apparent that the deviceof the instant invention provides a practical solution to the complexproblem of detecting low tires on operating vehicles, particularly thosevehicles equipped with dual wheels.

Although the invention has been herein shown and described in what isconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of theinvention, which is not to be limited to the illustrative detailsdisclosed.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

l. A device adapted to be mounted on a rotatable wheel having a hub anda concentrically related rim for indicating reduction in pressure for abody of fluid confined within a pneumatic tire mounted on said rimcomprising:

an hermetically sealed, tubular member formed of a flexible materialadapted to be affixed to the rim of said wheel in communication withsaid body of fluid, means for causing said member to assume an arcuateconfiguration for positioning the distal end of the member injuxtaposition with the hub of said wheel when the body of fluid ismaintained at a preselected pressure, and means including an enlargedmass affixed to the distal end of said member for deflecting said memberto a substantially linear configuration in response to centrifugalforces imposed thereon as said wheel is rotated when said pressure isreduced below said preselected pressure.

2. The device of claim 1 wherein said means for causing said member toassume an arcuate configuration includes an elongated, thickened portionof the wall of the tubular member, eccentrically related to thelongitudinal axis of symmetry thereof.

3. The device of claim 1 wherein said means for causing said member toassume an arcuate configuration includes an elongated, pleated portionof the wall of the tubular member, eccentrically related to thelongitudinal axis of symmetry thereof.

4. The device of claim 1 wherein said means for causing said member toassume an arcuate configuration includes an elongated leaf springaffixed to an elongated portion of the wall of the tubular member.

5. The device of claim 4 wherein said spring is characterized by alinear configuration when in an unstressed condition.

6. The device of claim 1 wherein said mass comprises a visuallydetectable flag affixed to the distal end of the tubular member.

7. The device of claim 6 wherein said means for causing said tubularmember to assume arcuate and linear configurations includes an elongatedleaf spring affixed to an elongated portion of a wall of the tubularmember.

l t h

1. A device adapted to be mounted on a rotatable wheel having a hub anda concentrically related rim for indicating reduction in pressure for abody of fluid confined within a pneumatic tire mounted on said rimcomprising: an hermetically sealed, tubular member formed of a flexiblematerial adapted to be affixed to the rim of said wheel in communicationwith said body of fluid, means for causing said member to assume anarcuate configuration for positioning the distal end of the member injuxtaposition with the hub of said wheel when the body of fluid ismaintained at a preselected pressure, and means including an enlargedmass affixed to the distal end of said member for deflecting said memberto a substantially linear configuration in response to centrifugalforces imposed thereon as said wheel is rotated when said pressure isreduced below said preselected pressure.
 2. The device of claim 1wherein said means for causing said member to assume an arcuateconfiguration includes an elongated, thickened portion of the wall ofthe tubular member, eccentrically related to the longitudinal axis ofsymmetry thereof.
 3. The device of claim 1 wherein said means forcausing said member to assume an arcuate configuration includes anelongated, pleated portion of the wall of the tubular member,eccentrically related to the longitudinal axis of symmetry thereof. 4.The device of claim 1 wherein said means for causing said member toassume an arcuate configuration includes an elongated leaf springaffixed to an elongated portion of the wall of the tubular member. 5.The device of claim 4 wherein said spring is characterized by a linearconfiguration when in an unstressed condition.
 6. The device of claim 1wherein said mass comprises a visually detectable flag affixed to thedistal end of the tubular member.
 7. The device of claim 6 wherein saidmeans for causing said tubular member to assume arcuate and linearconfigurations includes an elongated leaf spring affixed to an elongatedportion of a wall of the tubular member.